The present invention relates to air bearing sliders for carrying a transducing head in a disc drive. More particularly, it relates to an air bearing slider capable of operation at ultra-low flying heights.
Air bearing sliders have been extensively used in magnetic disc drives to appropriately position a transducing head above a rotating magnetic disc. In most high capacity magnetic storage applications, when the disc is at rest, the air bearing slider is in contact with the disc. During operation, the disc rotates at high speeds, which generates a "wind" of air immediately adjacent to the flat surface of the disc. This wind acts upon a lower air bearing surface of the slider and generates a force directing the slider away from the disc and against a load beam causing the slider to "fly" a small distance above the disc. A slider is typically mounted on a gimbal and load beam assembly which biases the slider toward the rotating disc, providing a spring force opposite to the bearing force of the wind incident on the air bearing surface of the slider.
For the disc drive to function properly, the slider must maintain the proper fly height, and the load beam assembly must provide adequate air bearing stiffness to assure that the slider does not contact the disc. Also, the air bearing slider must have a low take-off speed and low stiction at start up to limit disc contact and thus damage during take-off and landing of the slider. This is also important to limit slider wear.
As magnetic disc storage systems are designed for greater and greater storage capacities, the density of concentric data tracks on magnetic discs is increasing (that is, the size of data tracks and radial spacing between data tracks is decreasing), requiring that the air bearing gap between the transducer carried by the slider and the rotating magnetic disc be reduced. A requirement for achieving a small air bearing gap is increased disc smoothness. Increased disc smoothness leads to increased stiction between the disc and the air bearing surface of the slider. Increased stiction is detrimental because it requires increased energy during startup of the rotation of the magnetic disc.
One aspect of achieving higher data storage densities in magnetic discs is operating the air bearing slider at ultra-low flying heights. As air bearing slider flying heights reach ultra-low levels, contact between the transducing head on the air bearing surface of a slider and the magnetic disc are essentially unavoidable. When a disc drive is subjected to a mechanical hock of sufficient amplitude, the slider may overcome the biasing force of the load beam and lift off from the disc. Damage to the disc may occur when the slider returns to the disc and impacts the disc under the biasing force of the load beam. Such contact can result in catastrophic head-disc interface failure. Damage to the disc may occur which can result in loss or corruption of data or, in a fatal disc "crash," render the disc drive inoperable. Contact resulting in catastrophic failure is more likely to occur in ultra-low flying height systems.
There is a need in the art for a slider having an air bearing surface that will minimize catastrophic head-disc inter failure upon contact of the slider with the disc, while maintaining proper fly height and adequate air bearing stiffness. Also, there is a need in the art for a slider having an air bearing surface that will minimize stiction and friction between the slide and the surface of the magnetic disc.